Vitamin B12 Deficiency -- American Family Physician

www.aafp.org/afp AMERICAN FAMILY PHYSICIAN 979 manifestations (Table 1). It is a common cause of macrocytic (megaloblastic) anemia and, in advanced cases, pancytopenia. Neurologic sequelae from vitamin B12 deficiency include paresthesias, peripheral neuropathy, and demyelination of the corticospinal tract and dorsal columns (subacute combined systems V itamin B12 (cobalamin) plays an important role in DNA synthesis and neurologic function. Deficiency can lead to a wide spectrum of hematologic and neuropsychiatric disorders that can often be reversed by early diagnosis and prompt treatment. The true prevalence of vitamin B12 deficiency in the general population is unknown. The incidence, however, appears to increase with age. In one study, 15 percent of adults older than 65 years had laboratory evidence of vitamin B12 deficiency. The nearly ubiquitous use of gastric acid–blocking agents, which can lead to decreased vitamin B12 levels, may have an underappreciated role in the development of vitamin B12 deficiency. Taking the widespread use of these agents and the aging of the U.S. population into consideration, the actual prevalence of vitamin B12 deficiency may be even higher than statistics indicate. Despite these facts, the need for universal screening in older adults remains a matter of controversy.